This book was written to show that light is a primal element of life. All life originates and develops under the influence of the light of the sun, that "super terrestrial natural force" (Goethe). Sunlight influences the vital processes not onlyofthe plant (e. g. , heliotropism, photosynthesis) and the animal (e. g. , color change, maturation of the gonads) but of man as well. The human organism too reacts "heliotropically," as the 24 hour rhythm of the sleep-waking cycle demonstrates. of Artists have always perceived clearly the intensive stimulatory effect sunlight on their activity. One is reminded here ofCesare Lombroso, who wrote to his daughter "that thoughts come in the greatest profusion when (my) room is flooded with the sun's rays. " Richard Wagner exclaimed: "Ifonly the sun would come out, I would have the score finished in no time. " Bernard Shaw had a little cottage where he worked that could be turned according to the position of the sun. The composer Humperdinck wrote: "The sun is indispensable for my work; that is why it is important for me to have my study face east or south. " As these few examples indicate, it is above all those active in the arts who intuitively grasp the positive influence of sunlight on the psycho-physical effi ciency of their organism. In an age, however, when fluorescent lighting turns night into day, we are in danger of forgetting that man is a creature of nature as well as of culture.

Inhalt
1 Introduction.- 2 The Energetic Portion of the Optic Nerve.- Evolutionary History.- Physiological Findings.- Anatomical Findings.- 3 Light and the Pineal Gland.- Evolutionary History of the Pineal Gland.- Melatonin.- Light and Darkness.- The Influence of Light via Retina-Pineal Gland.- Interaction of the Pineal with Other Endocrine Glands.- Light and Color Change.- 4 Light and Growth.- The Influence of Light on the Growth and Development of Invertebrates.- The Influence of Light on the Development of the Human Body and Mind.- 5 Light and Body Temperature.- Diurnal Rhythm of Body Temperature in Adults.- Diurnal Rhythm of Body Temperature in Infants.- Disturbances in Temperature Rhythm Caused by Changes in Diurnal Rhythm.- Interruptions in Temperature Rhythm in the Blind.- 6 Light and Kidney Function.- Water Balance.- Electrolyte Balance.- Alteration in Diurnal Rhythm Caused by a Shift in the Daily Time Pattern.- Alteration in Diurnal Rhythm Caused by Rapid Change of Location.- Diurnal Rhythm in Children.- Forecast.- 7 Light and Blood Count.- Red Blood Cell Count.- Blood Sedimentation Reaction.- White Blood Cell Count.- Thrombocytes.- Eosinophilic Blood Cells.- 8 Light and Metabolic Functions.- Endogenic Lipid Metabolism.- Protein Metabolism.- Liver Metabolism.- Carbohydrate Balance.- Blood Sugar.- Insulin.- 9 Light and Thyroid Function.- 10 Light and Sexual Function.- Effects on Humans.- 11 Light and Adrenal and Pituitary Functions.- Cortisol and ACTH.- Catecholamines.- Pituitary Hormones.- 12 Natural Sunlight and Artificial Fluorescent Light.- Intensity.- Spectral Differences.- The Monotony of Artificial Lighting.- 13 Light Pollution.- 14. The Importance of Light in Metabolism in Man and Animal: Summary.- References.- Author Index.